Question

The image below shows Homologous Chromosome 4 from a Pea Plant. Carefully analyze this image. Then, answer the questions that follow.
Name one gene shown in the image.
Name the possible phenotypic alleles for that gene.
This plant is heterozygous for which gene(s)?

Answer 1

Answer No 1:

One of the genes shown in the diagram is for  flower position.

A gene can be best described as basic unit of heredity. A gene comprises of two alleles. The allele which masks the effect of the other allele is said to be dominant. The allele which gets masked by the dominant allele is said to recessive. The dominant allele is usually represented by a capital letter. The recessive allele is usually represented by a small letter.

The gene for axial flower position is dominant over the allele of terminal flower position.

Answer No 2:

The possible phenotypic alleles for that gene are the axial flower position and terminal flower position.

Phenotype can be described as those characteristics which can be observed.  They comprise of the physical properties of a trait.

In the above example, two of the flower positions, axial flower position and terminal flower position, can be seen and observed. Hence, these are the phenotypic traits.

Answer No 3:  

This plant is heterozygous for flower position and pod shape.

When the two alleles of a gene are different, they are termed as heterozygous. When the two alleles of a gene are similar, they are termed as homozygous.

As the allele of flower position are different  (Aa), hence they are heterozygous.

As the alleles for pod shape are different (Ii), hence they are heterozygous.

The alleles for height are however homozygous (tt).